We are continuing the viroid-host DNA hybridization studies to answer the question of whether there is a small degree of complementarity. What has been puzzling is our inability to compete a low level of hybridization with unlabeled viroid. Dr. Owens of Dr. Diener's lab, has generously provided us with cDNA to PSTV, which we will hybridize to viroids at high Cot values. We are also doing very high Cot studies using 125I viroid. The studies on the nature of the complementary RNA are continuing, attempting to determine its size, sub-cellular location and time course of appearance during the infection process. The cell suspension cultures will be utilized in attempts to study the mode of replication of PSTV, specifically, to see how closely the rate of viroid RNA synthesis is tied to general cellular RNA synthesis and the effects of various inhibitors of nucleic acid metabolism on incorporation of 3H-uridine into PSTV. We are continuing our attempts to purify ChCMV, which when purified will be fingerprinted. The symptomless strain will also be employed. Further experiments will be pursued to determine how x-ray irradiation may influence viroids in infected tissues.